MI: Fever in the Returning Traveller Flashcards by Phil Macanovic

How to take a good travel history

Where did you go (exactly) + Stopovers
Rural vs Urban
When did you go + timing of symptoms
Why did you go = (VFR - visting friends and relatives, higher risk)
Pre-travel vaccines / prophylaxis (malaria)

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List some diseases caused by mosquitoes.

Malaria
Elephantiasis
Dengue
Yellow fever
West Nile virus
Zika virus

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What is the vector for malaria?

Anopheles mosquito (female)

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What are the five species of Plasmodium.

Plasmodium falciparum (75%)
Plasmodium vivax (20%)
Plasmodium ovale
Plasmodium malariae
Plasmodium knowlesi

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Outline the life cycle of Plasmodium within humans.

Mosiquito bite infects humans with sporozoites
Within humans there is an exoerythrocytic stage (liver) and an erythrocytic stage
It replicates within liver and can remain dormant for years (vivax and ovale [hypnozoites])
It then infects erythrocytes and asexually reproduces, the ruptures to release the parasite

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Why does falciparum cause greatest mortality?

Invades RBCs of all stages
May be drug resistant

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What is the incubation time for malaria

Up to 1 month for falciparum

Longer for others

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Which malaria types is this?

Falciparum

Little headphones
More than one in each cell

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List the components of malaria prevention.

Awareness of risk
Bite prevention - repellants / nets
Chemoprophylaxis eg. malarone
Diagnose promptly and treat without delay

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Describe the clinical features of malaria.

Fevers - cyclical or continuous with spikes
Malaria paroxysms - chills, high fever, sweats

Usually 10-15 days after bite
Vivax - much longer - hypnozoite stage (liver)

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What is this?

Schizont
A malaria parasite which has matured and contains mainy merozoites
Indicative of severe malaria

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What is the definition of severe malaria?
List some clinical features.

High parasitaemia - >2% (low transmission areas) or >5% (high transmission areas) OR visualised schizont

Organ failures

Altered consciousness
Respiratory distress or ARDS
Circulatory collapse
Metabolic acidosis
Renal failure, haemoglobinuria (blackwater fever)
Hepatic failure
Coagulopathy +/- DIC
Severe anaemia or massive intravascular haemolysis
Hypoglycaemia

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What is the main investigation for malaria?

Perform 3 thick and thin blood films

Thick - screening for parasites (sensitive)
Thin - identifying the species and quantifying the parasite (proportion of red cells that have been parasitised)

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Which stain would you use in malaria blood film?

Field’s or Giemsa stain

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List two examples of malaria rapid antigen tests.

Paracheck-PF (plasmodial HRP-II)

OptiMAL-IT (parasite LDH)

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Outline the treatment options for non-falciparum malaria.

Chloroquine + primaquine

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What must you do before giving someone primaquine?

Screen for G6PD deficiency as primaquine can cause extensive haemolysis

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What are the complications of non-falciparum malaria?

Very rare but there are reports of splenic rupture

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What counts as ‘mild’ falciparum malaria?

Not vomiting
Parasitaemia < 2 %

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Outline the treatment options for mild falciparum malaria.

First line - artemisinin-based combined therapy (ACT) e.g. Riamet (artemether-lumefantrine)
Malarone (atovaquone and proguanil)
Quinine and doxycycline

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Outline the management of severe falciparum malaria.

ABCDEFG approch
Correct hypoglycaemia
Cautious hydration
Organ support if necessary
IV artesunate 1st line
(SEAQUMAT trial)
Daily parasitaemia monitoring
Follow on with oral antimalarials

Why is quinine not first-line in severe falciparum malaria?

Extensive side effects:

Cinchonism: tinnitus, dizziness, nausea and vomiting
Arrhythmias
Hyperinsulinaemia

What is the vector for dengue?

Aedes mosquito

What typs of virus is the dengue virus?

RNA virus with 4 main serotypes

Outline the clinical features of dengue.

Febrile phase lasts for around 4 days

What are the complications of dengue? In which circumstances does this tend to occur?

**Dengue haemorrhagic fever** and **dengue shock** - occurs in individuals who have previously been infected with a different dengue serotype and are then infected by another serotype

List some diagnostic tests for dengue.

* Blood/urine PCR * Serology (IgM 5-7 days) * RDT

How is dengue treated?

Identify those at risk of severe disease Supportive

What is the term used to describe a high temperature with a relatively normal heart rate? List some causes.

**Sphygmothermic dissociation** - typhoid, yellow fever, brucellosis, tularaemia

What is typhoid fever caused by?

*Salmonella typhi* and *paratyphi*

What type of organism is *Salmonella typhi?*

Gram-negative rod

Outline the clinical features of typhoid fever.

* High prolonged fever (no rigors) * Headache * Relative bradycardia (sphygmothermic dissociation) * Rose spots (rare) * Constipation * Hepatosplenomegaly * Dry cough

Describe the stages of typhoid?

1. Constipation, gradual rise in body temperature, relative bradycardia 2. Pesistant fever, hepatosplenomegaly, rose spots 3. GI bleeding, sepsis

What is the incubation period of typhoid?

7-18 days

List some complications of untreated typhoid.

* GI bleeding - congested Peyers patches * Perforation * Septicaemia * Encephalopathy

How is typhoid diagnosed?

- Cultures - stool, blood, bone marrow (rarely) - Serology ## Footnote Widel (RDT) - cheap but false positives

What is the treatment for Typhoid?

Oral rehydration solution Antibiotics - Uncomplicated empirical - azithromycin - Complicated - ceftriaxone

What is mononucleosis caused by?

EBV or CMV

What is a characteristic clinical feature of mononucleosis?

Tonsillar enlargement with exudates

List some investigations for mononucleosis.

* Monospot * IgM EBV/CMV NOTE: always consider HIV

What is a characteristic microscopic feature of mononucleosis?

Atypical lymphocytes

What is leptospirosis and how is it spread?

Infection caused by Leptospira (spirochetes) Commonly spread by rodents - associated with sewers and dirty water contaminated by rodent urine

Describe the clinical presentation of leptospirosis

Weil's - jaundice, renal failure, haemorrhage

How is leptospirosis diagnosed and treated?

Diagnosis - PCR serum/urine/CSF - Serology - IgM ELISA Treatment - Doxycycline - Ceftriaxone - Penicillin

What is Lyme disease and how is it spread?

Infection by Borrelia Spread by Ixodes ticks

Describe the clinical presentation of lyme disease.

How is Lyme disease diagnosed and treated?

Diagnosis - Clinical - ELISA - PCR blood/CSF (imperfect) Treatment - Doxycyline - Amoxicillin - Ceftriaxone in neuroborreliosis

What is lymphogranuloma venereum (LGV)?

STD caused by Chlamydia trachomatis (invasive serovars) Sexual transmission then travels from innoculation site into lymphatic system

Describe the clinical presenation of LGV

How is LGV diagnosed and treated?

Diagnosis - Serology - Direct fluorscent antibody test - PCR infected area/pus Treatment - Drainage of buboes/abscesses - Antibiotics - doxycycline (1st), azithromycin (2nd) (Contact tracing)